Supposedly “isolated” Russia’s bromance with China flourishes. No wonder: Both countries appreciate power politics and scoff at America’s display of global weakness.

President Obama pooh-poohed Moscow ever since his “reset” with Russia crashed and burned. He argued that under President Vladimir Putin Russia is an isolated country on the verge of bankruptcy.

That was then. On Tuesday, after months of snubbing the Kremlin, Secretary of State John Kerry came hat in hand to Sochi, Russia, where he tried to schmooze Putin and his foreign minister, Sergey Lavrov.

The Kremlin signaled its disdain for Washington by declining to confirm Kerry’s meeting with Putin until the last minute. Afterward, Kerry sheepishly said the sides weren’t seeking a “major breakthrough.”

While this haphazard attempt at diplomacy took place, the Russian and Chinese navies exercised together for the first time in the eastern Mediterranean — a symbol of a fast-gelling alliance between two growing military powers.

Beijing just invested $6 billion in a Russian rail project. Dozens of trade and other bilateral agreements address mutual interests in Central Asia.

And to address Beijing’s never-satiated hunger for energy sources and Moscow’s need for cash, Russia just signed a pact to build a lucrative natural-gas pipeline to China. Annual trade between the two countries is estimated at $100 billion.

Meanwhile, as cyber threats to America grow, including, prominently, from Chinese and Russian hackers, the two countries just signed a cyber non-aggression pact, raising fears about the future of Internet freedom.

And in the world of global diplomacy (Obama’s supposedly strong suit), Beijing and Moscow unite on United Nations Security Council votes that could harm them or their allies, blocking and vetoing American and other Western resolution proposals on Syria, Ukraine and, of course, anything to do with Beijing land grabs in the East and South China Seas.

Then there’s Kerry.

He said he’d talk to Putin and Lavrov about Russia’s aggression in Ukraine, its unyielding support for Syrian President Bashar Assad and its backing of other unsavory alliances around the world.

But he had little to offer Tuesday beyond platitudes. Kerry said he’d raise Russia’s sale of the S-300 air-defense missile system to Iran. Russian officials said he didn’t even bring it up.

So who’s really isolated here, their aggressive power players, or our hapless diplomats?

Over the weekend Putin threw a party, a Moscow military parade commemorating the end of World War II.

It was a throwback to the Cold War days, when the Soviets would flex their muscles publicly to scare everyone off. Obama snubbed the Kremlin invitation, and so did most of our Western European allies, who stayed away from the parade.

Chinese President Xi Jinping, however, did not. He was seated quite comfortably right next to Putin. Xi waxed poetically about the historical Russian-Chinese alliance since fighting together in WWII.

Once upon a time Henry Kissinger knew how to exploit Sino-Russian tensions to pull one of the Cold War’s biggest coups. Nixon went to China, stealing away one of Russia’s best potential allies, and the rest is history.

But that was when we’d flex some muscle around the globe, too, resisting Communism everywhere until it collapsed under its own weight. Now Putin swallows parts of Europe and props up his nasty Mideast allies and China forever pushes the envelope in its aggression against Asian neighbors.

While Obama fights with Democrats on the Hill over a trade deal with our Pacific allies, Putin makes a reality of his own “pivot” to Asia.